hmmmm Well, near as I can tell (not being familiar with the song)

She doesn't feel special
She knows others think she is, and she'll accept that
but she doesn't really believe it, except when you say it
then she does, but only for awhile, until you finally see what she really is
and then you won't think so anymore.

Of course, she could stay special for you
she hopes she can, and she hopes you'll stay, even if she isn't.

That's my take.